\documentclass[tikz,border=10pt]{standalone}
\usepackage{tikz}
\usetikzlibrary{positioning}
\usepackage{tikz-feynman}
\begin{document}

\begin{tikzpicture}
	\begin{feynman}
		%% fig a
		\vertex (a1) at (0,0);
		\vertex[right =1cm  of a1] (a2);
		\vertex[right =2cm  of a1] (a3);
		\vertex[right =3cm  of a1] (a4);
		\vertex[right =4cm  of a1] (a5);
		\vertex[above =1cm of a3,crossed dot] (a6){};
		\node[above =1.5cm  of a5] {};
		% 对各个顶点连线
		\diagram*{
		{ [edge= fermion]
		(a1) --[momentum'={\scriptsize \(p-k\)}]  (a5),
		},
		% 介子连线
		{ [edge= charged scalar]
		(a2) --[quarter left, momentum={\scriptsize \(k\)}](a6)--[quarter left,momentum={\scriptsize \(k+q\)}](a4),
		}
		};
	\end{feynman}
\end{tikzpicture}

\end{document}
